arraylist in JAVA | Java Language | Coding Winds

ARRAYLIST

Hey guys, we are back with another blog, in this we are talking about arraylists in java. So happy reading and do let us know your views on this in the comment section below.

Arraylist is another kind of array in java, but in this you can do certain operations and customizations, also the size of an arraylist is not fixed. So before implementation, we need to import the array list class i.e., import java.util.ArrayList;

After importing the arraylist class we have to create an object, let’s see the syntax

ArrayList <Type> name = new ArrayList();

Now after creating an object we can add the values of the type that we have already wrapped within the angular brackets when we made the arraylist object, to add values we use the add() function and we put the values to be added inside the parentheses, separately for each value.

Ex:

package arrayList;

import java.util.ArrayList;

 

public class myArrayList {

 

     public static void main(String[] args) {

    

         ArrayList <Integer> marks = new ArrayList();

         marks.add(99);

         marks.add(85);

         marks.add(71);

         System.out.println(marks);

     }

 

}//Output: [99, 85, 71]

 

Also the point to be noted here is that we use the proper word to declare the type i.e., ‘Integer’ instead of ‘int’, same holds with the char type we will use ‘Character’ (inside the angular brackets) if we want our element to be of type char. Also (as shown above) in order to view the elements of an arraylist one doesn’t needs to use a loop, they can just print the name of the arraylist object.

Now let’s see another example in which we add char type in our arraylist.

import java.util.ArrayList;

 

public class myArrayList {

 

     public static void main(String[] args) {

    

         ArrayList <Character> xyz = new ArrayList();

         xyz.add('C');

         xyz.add('o');

         xyz.add('d');

         xyz.add('i');

         xyz.add('n');

         xyz.add('g');

         xyz.add('W');

         xyz.add('i');

         xyz.add('n');

         xyz.add('d');

         xyz.add('s');

         System.out.println(xyz);

     }

 

}//Output: [C, o, d, i, n, g, W, i, n, d, s]

 

Similarly if we add Strings in our arraylist we will wrap it within double quotes inside the parentheses after add.

Now let’s us see how can we take user inputs in our arraylist, below is the example which demonstrates how can we take user inputs for a string type

import java.util.*;

 

public class myArrayList {

 

     public static void main(String[] args) {

         Scanner sc = new Scanner(System.in);

    

         ArrayList <String> fruits = new ArrayList();

         fruits.add(sc.nextLine());

         fruits.add(sc.nextLine());

         fruits.add(sc.nextLine());

 

         System.out.println(fruits);

      

     }

 

}//Output: [banana, orange, pineapple]

 

So now let’s talk about some of the functions that can be used for arraylist :

    i) .get(index) : 

So basically the get keyword gets us the value of the element at the index (that will be inside the parentheses following get.

Ex:

import java.util.*;

 

public class myArrayList {

 

     public static void main(String[] args) {

         Scanner sc = new Scanner(System.in);

    

         ArrayList <String> fruits = new ArrayList();

         fruits.add("banana");

         fruits.add("orange");

         fruits.add("pineapple");

         System.out.println(fruits.get(2));

      

     }

 

}//Output: pineapple

    ii)add(): 

We have already seen the use of the add() function but we can also use this function to add an element at specific index.

Ex:

import java.util.*;

 

public class myArrayList {

 

     public static void main(String[] args) {

         Scanner sc = new Scanner(System.in);

    

         ArrayList <String> text = new ArrayList();

       

         text.add("Winds");

         text.add(0, "Coding");

         System.out.println(text);

          }

 }//Output:[Coding, Winds]

 

    iii).set(index, value):  

Set functions modifies (or replaces) the value of the element at the specified index.

Ex:

import java.util.*;

 

public class myArrayList {

 

     public static void main(String[] args) {

         Scanner sc = new Scanner(System.in);

    

         ArrayList <String> text = new ArrayList();

       

        text.add("Coding");

        text.add("Winds");

        text.set(0,"Hello");

        text.set(1, "People");

         System.out.println(text);

          }

 }//Output:[Coding, People]

 

     iv).remove(index): 

This function removes the element at the specified index.

Ex:

import java.util.*;

 

public class myArrayList {

 

     public static void main(String[] args) {

         Scanner sc = new Scanner(System.in);

    

         ArrayList <String> text = new ArrayList();

       

        text.add("Coding");

        text.add("Winds");

       text.remove(1);

         System.out.println(text);

           }

}//Output:[Coding]

 

    v).remove():  

This function is used to clear or delete all the elements from the arraylist.

Ex:

import java.util.*;

 

public class myArrayList {

 

     public static void main(String[] args) {

         Scanner sc = new Scanner(System.in);

    

         ArrayList <String> text = new ArrayList();

       

        text.add("Coding");

        text.add("Winds");

       text.clear();

         System.out.println(text);

          }

 }//Output:[]

    vi).size(): 

This tells us the size of the arraylist in java.

Hope you are clear on this  topic do read our more articles on JAVA LANGUAGE.

If you still have any doubt on this topic then do come to us via email "sophomoretechs@gmail.com" or via Instagram "@coding.winds".

This article is SUBMITTED By : Pranjal Rai

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